Abstract: A suck-back pump for preventing any additional amount of liquid from dropping out of the tip of a delivery pipe, after a predetermined amount of liquid has been delivered from the delivery pipe. The suck-back pump includes inlet and outlet ports for liquid, first and second chamber respectively connected with the inlet and outlet ports, a communicating passage for connecting the first and second chambers with each other, a shut-off valve movable to close the communicating passage, and a suction element movable to change the volume of the second chamber. The actuation of the suction element is retarded so that it is actuated after the shut-off valve has been actuated.